DESCRIPTION: (Applicant's Description) The specific goals of the Eicosanoid Analysis Core are to carry out the analyses of eicosanoids in complex biological fluids and tissues for investigators in this Program Project Grant. The four projects proposed in this Program Project Grant involve research examining the role of the cyclooxygenase and eicosanoids in colorectal neoplasia and will require quantification of prostaglandins (PGs). Eicosanoids will be quantified in cellular incubations and animal and human tissues by methodology employing capillary gas chromatography (GC)/electron capture negative ion chemical ionization (NICI) mass spectrometry (MS) using stable isotope dilution techniques that were developed by the Core Leader and which are currently in use. Use of these assays by investigators involved in this Program Project Grant has already allowed a number of fundamental observations to be made that have helped to delineate the role of eicosanoids in pathophysiological processes related to gastrointestinal malignancy. In addition, the Core will also develop a GC/NICI MS assay to measure the compound 12- hydroxy-heptadecatrienoic acid (12-HHT) derived from the cyclooxygenase-generated bicycloendoperoxide intermediate PGH2. This assay will be utilized in Project 4 (Dr. Marnett) to further explore the role of 12-HHT in situations of cyclooxygenase overexpression. The overall objectives of the Eicosanoid Core, therefore, are to provide technical support and implementation of highly sensitive methodology for the quantitative analysis of eicosanoids.